82410 • 82710 • 82910 WSM, 12271
(3) Crankshaft
11790F10060
(4) Piston and Piston Rings
11790F10070
11900F10040
1 ENGINE
The crankshaft with the connecting
rod
converts the
reciprocating motion of the piston into the rotating
motion.
The crankshaft
is
made of tough special alloy steel,
and the journals, pins and oil seal sliding portions are
induction hardened to increase the hardness for higher
wear resistance.
The front journal is supported by a solid type bearing,
the intermediate journal by a split type, and the rear
journal by a split type with thrust bearings.
The crankshaft
is
provided with an oil gallery, through
which engine oil
is
fed to the crankpin portion, and
lubricates it.
11790M10040
The piston has a slightly oval shape when cold
(in
consideration of thermal expansion) and a concave
head.
Three rings are installed
in
grooves
in
the piston.
The top ring (1) is a keystone type, which can stand
against heavy loads, and the barrel face on the ring fits
well to the cylinder wall.
The second ring (2)
is
an undercut type, which
effectively prevents the oil from being carried up.
The oil ring (3) has chamfered contact faces and an
expander ring, which increase the pressure of the oil ring
against the cylinder wall.
Several grooves are cut on the top land to help heat
dissipate and to prevent scuffing.
(1)
Top Ring
(4)
Depression
(2)
Second Ring
(5)
Valve Recess
(3)
Oil Ring
11900M10041
1-M3
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